Diodes and switching means as well as an autotransformer connect multiple AC sources of variable frequency and voltage to the utility grid, without first rectifying and thereby transferring the AC input energy to a common DC bus. Instead, the individual positive and negative AC input half waves or parts of those half waves, if and when they occur during a particular time interval, are injected into the positive or negative half wave of the utility AC power directly and respectively. The amount of energy transferred may be controlled by a microprocessor. Assuming the prime mover that generates AC voltages in multiple coils is a windmill, then the required circuitry to accomplish this energy transfer will be physically small enough to allow that circuitry to reside in the windmill itself, and thereby this energy conversion method significantly simplifies the installation of a windmill that uses this energy conversion method.